In the related art, in order to improve optical characteristics of sunglasses, a technique of using a discoloration lens configured to react with ultraviolet light or a liquid crystal configured to simply vary transmissivity has been proposed. However, when the discoloration lens is used, the discoloration lens cannot be easily used at night or in a vehicle in which an ultraviolet light shielding glass is installed, and is largely affected by a temperature in a use environment. In addition, in the case of the technique of using the liquid crystal for the purpose of simple transmissivity adjustment, use of the technique is limited because the technique cannot deal with surrounding illuminance. Accordingly, improved sunglasses and goggles capable of easily adjusting various optical characteristics according to variations in environments are needed.